All-electric vehicles, such as road vehicles or rail vehicles, run on electricity only. They are propelled by an electric motor which may be powered by on-board batteries requiring periodic recharging from an external, usually stationary, source. However, a major drawback with electric vehicles concerns their range. After an electric vehicle is driven for some distance and/or time, it is required that the vehicle be recharged at a charging station. Most all-electric cars take a long time to recharge their on-board batteries, thereby requiring substantial downtime.
The above drawbacks also apply to electric aircraft. In particular, propeller-driven electric aircraft have limited range due to inadequate energy cell (or battery) capacity and limited power characteristics (e.g., with respect to wattage, amperage, energy discharging rate, charging rate). To date, there are no Federal Aviation Administration certified all-electric aircraft flying as a result of this problem.
Increasing the number and/or size of batteries or energy cells in attempt to extend range of flight is impractical and undesirable because doing so increases the weight of the aircraft and changes the load distribution in the aircraft. It is well known that weight and balance limits of any aircraft are critical to flight safety. The increase in weight and shift in the aircraft's center of gravity compromise flight characteristics of the aircraft and can jeopardize flight safety. For example, operating near or above the maximum weight limitation weakens the structural integrity of the aircraft and adversely affects flying performance. Operation with the center of gravity outside the approved limits results in flying control difficulty.
Other approaches, such as integrating a generator into the propeller shaft or mounting turbine generators outside the aircraft extending beyond the aircraft's aerodynamic profile, are also undesirable because they rob the propulsion motor of power and change the aerodynamics of the aircraft. Further, solar panels mounted on an aircraft's exterior skin fail to provide adequate power to both the motor and on-board electronics and can adversely affect flight characteristics.
Another approach to resolving the inadequate battery capacity of electric vehicles is to provide a power regeneration system. One such device is described in U.S. Pat. No. 8,509,992 to Bosworth. Bosworth describes a system for a car to recharge a battery using atmospheric wind. The system includes a wind-driven turbine, an alternator, and a vehicle battery connected to the alternator, wherein upon rotation of the turbine, the alternator generates electricity to charge the battery. However, this system is rendered ineffective and does not provide recharging capability if there is minimal or no atmospheric wind, or the wind is not directed toward the air intake scoop and turbine, or if the vehicle is stationary. For example, when the vehicle is parked with the engine running (e.g., warming up the car in the garage, car stopped at a street light) the battery is being depleted and not recharged. The Bosworth system also does not control the charging-discharging of a plurality of batteries and does not coordinate which batteries power the vehicle's motor and electronics, which batteries remain idle, and which batteries undergo recharging. Instead, Bosworth teaches that the generated electricity is used to charge one vehicle battery or to directly power the electric motor. During times when the system is charging the vehicle battery as opposed to powering the electric motor, then a conventional combustion engine is needed to propel the vehicle. That is, the Bosworth system is designed only for hybrid vehicles and does not function to power all-electric vehicles. Moreover, this system is not adapted for an aircraft and does not address the issues related to maintaining flight characteristics, load distribution and aerodynamics of the aircraft.
U.S. Pat. No. 3,076,510 to Piel is directed to a wind-propelled electric generator for moving vehicles. Upon harnessing atmospheric wind energy, the generator produces electricity which is stored in a battery. The wind-driven generator may be mounted in and protrude from the leading edge of an aircraft wing or it may be mounted to protrude from the nose. However, the Piel system is not designed to utilize propeller blast and does not recharge multiple batteries that become depleted as a result of powering the vehicle's motor and electronics during normal flight operations. Piel explicitly teaches that the generator serves as an auxiliary generator for emergencies, or as an additional electric generator for a vehicle having a standard motor driven generator. Additionally, the mounting of the generator such that it protrudes from the leading edge of the wing changes the aerodynamics and flight characteristics of the airplane.
U.S. Pat. No. 3,876,925 to Stoeckert and U.S. Pat. No. 8,791,586 to Ortiz et al. each describe a system involving a wind turbine driven generator. Each system is implemented in an automobile and comprises scoops that rotate an armature in the presence of wind, wherein rotation of the armature generates electricity for charging storage batteries. The systems of Stoeckert and Ortiz are not configured for an all-electric aircraft and are merely designed to harness atmospheric wind energy. They do not harness energy from the blast of an aircraft propeller. Further, Stoeckert and Ortiz do not provide a controller that controls the charging-discharging of the batteries and determines which batteries power the electric motor, which batteries remain idle, and which batteries undergo recharging. Their systems do not include a charge controlling device which monitors the velocity of the propeller blast and provides a constant charging level if the blast velocity varies.
Accordingly, in view of prior art systems, there is no on-board aircraft solution, without compromising aircraft weight and/or performance, for regenerating or increasing battery capacity in flight to extend range of travel. It would be beneficial to provide a regenerative system which recharges one or more energy cells without relying on the presence of atmospheric wind or requiring constant motion of the vehicle. It is further beneficial to provide a regenerative system configured for implementation in an all-electric or hybrid propeller aircraft. It is also beneficial to provide a regenerative system that imposes minimal change in flight characteristics and aerodynamics of the aircraft.